1. Field of the Invention
This invention relates to a pipe for underdraining.
2. Description of the Prior Art
Since prior art pipes for underdraining have through holes on the pipe wall and nothing else, various filter materials such as rubbles, gravels, chaffs and the like are disposed around the pipe for the purpose of preventing choking of the through-holes and enhancing the water-collecting capacity. However, it is very difficult to prevent completely clogging and further the working is complicated and requires many hands.